By means of electrochemical fuel cells, reactants, like a stream of hydrogen and a stream of oxygen can be converted into electric power and water. For example with polymer electrolyte fuel cell designs, an electrolyte membrane is typically interposed between an anode and a cathode to form a membrane electrode assembly (MEA). Since a single fuel cell only provides a rather limited maximum voltage, a pre-determined number of fuel cells are typically stacked on one another or next to each other to form a fuel cell stack, wherein adjacently disposed fuel cells are electrically contacted in series.
With proton exchange membrane fuel cells (PEMFC) but also with other fuel cell designs when making use of gaseous reactants it is necessary to precisely control the gas flow within the stack. In order to provide a gas tight sealing, a fuel cell stack sufficiently equipped with sealing elements is typically compressed along the stacking direction, e.g. by way of two end plates arranged at opposite ends of the fuel cell stack that are directly interconnected with each other by way of tension bolts.
However, such a fuel cell design is rather difficult to assemble since the various fuel cells, MEAs, sealing elements and separating structures may be twisted in a plane perpendicular to the stacking direction. As well, the entire fuel cell stack may be rather prone to torsion forces in use.
From document EP 1 936 729 A1 a casing for a fuel cell stack is known. There, the stack body is held in a casing including end plates. The casing also includes a plurality of separate side plates provided on sides of the stack body. End plates and side plates are coupled by coupling pins, wherein each of the side plates has a plurality of separate coupling portions adapted to receive the coupling pins. In effect, tension forces between the end plates have to be transferred via a plurality of coupling pins and corresponding coupling portions that may form a weakening spot being subject to considerable point loading in use. Moreover, the mutual interconnection of end plates and side plates is quite laborious. Also, an interconnection of side plates further requires separate assembly of angle profiles in a respective corner region.
It is therefore an object of the present invention to provide a housing assembly of improved stability, especially against torsion effects. Moreover, the housing assembly should be easy and intuitive to assemble. It should be long lasting, robust and light weight and also cost-efficient in production and assembly.